利用多晶硅切割废料制备SiC粉体

Preparation of SiC powder by using polysilicon cutting waste

针对目前多晶硅切割废料大量堆积造成环境污染的问题,提出了以多晶硅切割废料为原料,经过盐酸浸出除Fe后,配加活性炭高温反应制备SiC的工艺。首先,对废料成分与碳的反应进行了热力学计算;然后,使用差热分析、X射线衍射和扫描电子显微镜等分析手段,研究了反应温度、反应时间以及废料中的Fe对产物物相组成和形貌的影响。结果表明,切割废料经过酸浸后的主要成分为SiC和Si。碳不能与Fe-Si系合金(FeSi、Fe_5Si_3等)中的Si反应生成SiC,所以为了制备纯度较高的SiC,多晶硅废料反应前必须预先除Fe。当反应温度高于1 400℃时,酸浸后的切割废料与活性炭的反应能够迅速地发生,且反应生成的SiC遗传碳颗粒的形貌。

In view of the serious environmental pollution problems caused by the current large accumulation of polysilicon cutting waste,a process to prepare SiC by adding activated carbon to high temperature reaction was carried out by using the polysilicon cutting waste as raw material. The polysilicon cutting waste was leached by HCl solution to remove the impurity Fe. Firstly,the thermodynamics of the reactions between the components in waste and carbon was calculated. Then,the differential thermal analysis（DTA）,X-ray diffraction（XRD）and scanning electron microscope（SEM）were used to analyze the effects of reaction temperature,reaction time and impurity Fe on the phases and morphology of the products. It is found that the main components of the cutting waste after hydrochloric acid leaching are silicon carbide and silicon. The iron must be removed in advance before high temperature treatment because the carbon cannot react with Fe-Si alloy（FeSi,Fe_5Si_3,etc.）to generate SiC.When the reacted temperature is higher than 1 400 ℃,the reaction between activated carbon and the treated waste is quick,and silicon carbide with high purity is obtained. Meanwhile,the morphology of the produced SiC particles are the same as that of the carbon particles.